We will attempt to determine the linkage of the group B capsular type antigen to the cell wall. Type antigen will be released by muralytic enzymes and the soluble as well as the insoluble material subjected to complete compositional analysis. It is expected that by following murein components and rhamnose content a clue to the nature of the cross-links will be obtained. The Ibc protein will be characterized and its subunit structure determined. Analogous proteins will be sought in serotypes Ia, II, and III and, if found, tested for their relevance to pathogenicity.